This invention relates to digital encoding devices and, more particularly, to a rotary encoder for use in adding scratch effects to digital signals, especially audio signals.
The rapid replacement in recent years of the analog, vinyl phonograph disc with digital signal sources, notably the compact disc (CD), has, for the most part, been enthusiastically received. It seems difficult to believe that this transition in audio signal sources could possibly have any drawbacks. However, disc jockeys and the like who use various audio signal sources for providing entertainment over the radio or in more local settings have discovered at least one disadvantage. Disc jockeys, or DJs as they are often. called, use physical manipulation of one or more phonograph records to create myriad special audio effects. Some of these manipulations are called xe2x80x9cscratchingxe2x80x9d or, in more formal settings, turntablism. DJs use special turntables and special turntable slip mats which allow controlled slippage between the disc and the turntable platter, as well as other specialized equipment to perform these manipulations. There are schools and workshops where an aspiring DJ may enroll to learn the fine points of these manipulations. As in any specialized field, names like baby scratch, hamster style, twiddle scratch, bubble scratch, tear scratch, etc. all have specific and well recognized meanings within the DJ fraternity.
The problem is that the vast majority of these effects involve, at least in part, physical manipulation of a record on a turntable to alter the sound. Once a digital signal source such as a CD is used, no physical manipulation is possible. Attempts have been made to simulate some of the well known scratch effects using digital signal processing techniques on an audio signal, regardless of its source.
U.S. Pat. No. 5,512,704 for ELECTRONIC SOUND SIGNAL GENERATOR ACHIEVING SCRATCH SOUND EFFECT USING SCRATCH READOUT FROM WAVEFORM MEMORY, issued Apr. 30, 1996 to Jun Adachi, teaches one such apparatus for generating a scratch sound effect in combination with a musical instrument or other electronic sound generator. ADACHI""s scratch effect is applied to individual tones being generated within the musical instrument, by controlling the rate and direction of readout of a digitized waveform from memory within the musical instrument.
In contradistinction, the inventive system uses a record-like transducer as an input to a digital signal processor. By using specific algorithms, physical manipulations of the inventive transducer which simulate the well-known manipulations of a disc may be used as input to a digital signal processor (DSP). These input signals may then be used to alter the digital stream being fed to the DSP such that the anticipated effect is close, possibly even indistinguishable from an analog, hand-generated scratch effect. ADACHI teaches no such transducer nor does he teach the scratching of an audio stream from a CD player or other such signal source.
U.S. Pat. No. 5,350,882 for AUTOMATIC PERFORMANCE APPARATUS WITH OPERATED ROTATION MEANS FOR TEMPO CONTROL, issued Sep. 27, 1994 to Satoru Koguchi, et al., teaches an encoder for changing the direction and/or tempo of the performance of a musical instrument. A disc moved by a performer in either a forward or reverse direction at a particular velocity generates timing signals which may be interpreted to set the tempo or another parameter of a performance.
The encoder of the present invention is adapted to simulate in size, speed, and feel the familiar phonograph record so that a DJ, having perfected often difficult disc manipulations, may transfer his/her knowledge to a new medium without need for extensive retraining and/or practice. KOGUCHI, et al. provide no such encoder nor do they teach the application of their apparatus to a digital audio signal stream comprising music from a CD or a similar signal source.
U.S. Pat. No. 5,159,143 for INFORMATION RECORDING MEDIUM PLAYER FOR CONTROLLING MUSICAL DEVICES USING A MUSICAL INSTRUMENT DIGITAL INTERFACE (MIDI) FORMAT SIGNAL, issued Oct. 27, 1992 to Tetsuro Emi, et al., teaches the combining of MIDI control information on a CD or similar signal source. Using this technique, predefined control information is available to allow a MIDI-equipped musical instrument to xe2x80x9cplay alongxe2x80x9d with the prerecorded music. EMI, et al. do not teach the generation of any scratch effect using a rotary encoder.
U.S. Pat. No. 4,813,327 for MUSICAL TONE CONTROL SIGNAL GENERATING APPARATUS FOR ELECTRONIC MUSICAL INSTRUMENT, issued Mar. 21, 1989 to Yasunao Abe, discloses a device for bending pitches being generated by a musical instrument. There is no teaching of any apparatus or method for adding scratch effects to an audio signal supplied from a digital signal source such as a CD.
U.S. Pat. No. 5,256,832 for BEAT DETECTOR AND SYNCHRONIZATION CONTROL DEVICE USING THE BEAT POSITION DETECTED THEREBY, issued Oct. 26, 1993 to Atsushi Miyake, teaches a device for detecting a beat position in an audio signal. The intended use of the MIYAKE apparatus is in providing synchronization between tracks in a multi-track recording environment. While beat detection could and typically would be useful in producing certain well-known scratch effects, much more information is needed to produce those effects. MIYAKE teaches no rotary encoding device nor is there taught any method for producing scratch effects in an audio signal stream.
U.S. Pat. No. 6,025,552 for COMPUTERIZED MUSIC APPARATUS PROCESSING WAVEFORM TO CREATE SOUND EFFECT, A METHOD OF OPERATING SUCH AN APPARATUS, AND A MACHINE-READABLE MEDIA, issued Feb. 15, 2000 to Hirofumi Mukaino, et al., teaches an apparatus and method for adding pseudo scratch effects to digitally encoded sounds. Both a pad and a ribbon controller are utilized to control the generation of the scratch effects. MUKAINO, et al., however, do not teach a disc-like rotary encoder for generating scratch control input signals.
U.S. Pat. No. 5,065,013 for OPTICAL ENCODERS USING TRANSMITTED AND REFLECTED LIGHT DETECTION AND HAVING COMPLEMENTARY OUTPUT, issued Nov. 12, 1991 to Robert M. Taylor; U.S. Pat. No. 5,569,912 for OPTICAL VELOCITY MEASURING WITH EFFICIENT USE OF RADIATION PASSING THROUGH PATTERNS OF DISCS, issued Oct. 29, 1996 to Everardus T. G. Turk, et al.; and U.S. Pat. No. 5,763,874 for INCREMENTAL OPTICAL ENCODER HAVING PARTIALLY OPAQUED QUADRATURE DETECTORS, issued Jun. 9, 1998, all teach rotary optical encoders possibly suitable for constructing a disc-like rotary encoder for use with the present invention. However, none of these patents teaches such an encoder or suggests the use of such an encoder in an application such as generating scratch effects in a digitized audio signal supplied from a digital signal source such as a CD.
None of these patents, either individually or in combination, teaches or suggests a disc-like rotary encoder for creating scratch effects in an audio signal from a digital signal source.
It is therefore an object of the invention to provide a rotary encoder simulating a phonograph record for use as an input device to a digital scratch effect apparatus.
It is a further object of the invention to provide a rotary encoder simulating a phonograph record having a feel simulating a vinyl disc on a conventional turntable.
It is an additional object of the invention to provide a rotary encoder simulating a phonograph record which is intuitive to use.
It is another object of the invention to provide a rotary encoder simulating a phonograph record providing both speed and direction signals to a microprocessor-based digital signal processor for generating scratch effects.
The present invention provides a rotary encoder having the physical characteristics of a vinyl phonograph disc on a properly prepared turntable. A disc jockey (DJ) may intuitively use this encoder in a manner virtually identical to a conventional record and turntable to create scratch effects in a digitized musical signal being supplied from a digital signal source such as a CD, mini-disc, digital audio tape (DAT) or any other source of a musical signal. Speed and direction information from the encoder are used as inputs to a digital signal processor so that scratch effects typically produced by the manipulation of a vinyl record on a turntable may be simulated in the digital audio signal. The digital signal processing may be accomplished by a dedicated digital signal processor or by a digital signal processing program running on a general purpose digital computer such as a personal computer (PC).